|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
71.126.132.235
I've ordered a few things recently in a total overhaul of my system. I'm turning the entire amplification system (phono stage, preamp, head amp, and power amp) from solid-state to tubes. I've had some tube stuff before -- head amps, the Jolida JD100, that sort of thing -- but have never really had the full tube experience. That's about to change, thankfully... I got four things:- A DIY 45/2A3 SET amplifier ("DIY" meaning "somebody else did it himself");
- An Antique Sound Lab MG Head 32 preamp/headphone amp;
- A Ming Da MC767-RD phono stage (which presents a problem; read on);
- A did-it-himself Bottlehead Foreplay II preamp, completely tricked out. Outboard power supply half the size of the main chassis, the two biggest capacitors I've ever seen, nice stepped attenuators, tube rectifiers and regulators in addition to the 12AU7s, and a great finish. I don't really need this with the ASL, but I decided to go ahead and get it and maybe switch between the two depending on mood. They're bound to sound different.1) How do I get shocked handling tubes? Would it be by accidentally brushing the pins while there's still a charge in it? I just don't see how you could deal yourself a lethal voltage by touching the glass alone, as that's not a good conductor... it'd probably be easier to burn yourself than to shock yourself, but everything I've seen with bigger power tubes and whatnot has come with a stern warning not to kill yourself.
2) How do I not kill myself with big power tubes? Preamp tubes can store enough current to keep playing for about ten seconds after the power is shut off -- that's quite a bit of power for a dinky little valve. Lord knows what a power tube would be like... when turning off the Bottlehead, I wait for the rectifier to go out/stop glowing, which takes maybe some 15 seconds, and then I figure I'm good to go.
3) The Ming Da uses the infamous 6N6T rectifier tube, available seemingly only in China and nowhere else in the whole world. I've searched for it on this forum and found just about nothing... not too great a sign. The only useful bits I could find were that it's not interchangeable with the more common 6N6R (or 6H6P in Cyrillic) and that the elusive 6N6T can be found at audiotriodes.com. Excellent: except I can't find it there under the name 6N6T. There are 6N6 tubes available for about ten Euros apiece, marked just as 6N6. Are these the ones?
4) How hard is it to redo a tube socket? There's the obvious danger of killing your amplifier, but it might be worth it if I can convert the 6N6T into something a little more readily available (not just from one store from one manufacturer on the entire internet -- if that's even the right tube). Maybe I'll just use the Ming Da until that tube dies and then switch to a different phono stage. I got the stuff I did because it was cheap and because I'm not at all rich or even moderately wealthy... now I'm seeing where the cut corners are coming in. This might be a mercifully cheap lesson: don't buy cheap Chinese crap. I'm a bit disappointed in myself for buying Chinese at all, to be honest (the ASL is used so that's different).
5) Finally, what tubes should I roll first? This is probably a really common question so I apologize. I'm on a limited budget so I've got to pick carefully; I've got maybe $200 to spare, so I could get a very few NOS ones in the right places or I could deck it out in current-production tubes. I'd lean towards maybe the Ming Da, as it probably comes with cheap Chinese ones. The ASL is secondhand and I have no idea if the owner has kept in the stock tubes or if he's swapped them out, so that's a maybe. As for what to roll--
I figure rectifier tubes have a minimal impact on the sound if any, so I'll just get a backup for them and move along. Regulators, I'm not so sure about. How much do these affect the sound? I'll probably make them my next-lowest priority under rectifiers -- that is, if they don't cause a night-and-day difference. That brings us to stuff actually in the signal chain, and that's where I've got a bunch of options. I guess I may as well give the tube complements, because that'll certainly help:
MG HEAD 32: 5Y3 (x1, rectifier); 6BQ5 (x4, drive); 12AU7 (x2)
MING DA: 6N6T (x1, rectifier); 12AX7B (x1, regulator); 5687 (x1, regulator); 6N3 (x2)
AMPLIFIER: 5R4 (x1, rectifier); 6SL7 (x1, drive); 45 or 2A3 (x2 -- it comes with 45s. 2A3s aren't at all cheap, so I think I'll pass on getting any of these for a while)
BOTTLEHEAD: 6X4 (x1, rectifier); 0A2 (x2, regulators); 12AU7 (x2)
Even subtracting the rectifiers and maybe regulators from the equation, that's a lotta tubes to roll. Thirteen, if I counted right. As for my listening habits -- if this helps -- it's speakers during the day at moderate volume, louder speakers in the evenings, and headphones at night. Night listening is my favorite, so the head amp is high on the list. Sound preferences: lush, "bloomy", colorful, tuneful... in other words, not SS. I don't get "good sound" confused with "high fidelity". Give me coloration or give me death! Music preferences are rock 'n' pop and classical; almost exclusively male vocals. I have no idea why female vocal music is so popular among audiophiles... I can't stand the stuff.
This is a loooooong post, but I'd appreciate the assistance, even if this kind of stuff has to have been asked before. I'd just like it tailored towards what I need to know, you know?
Follow Ups:
As far as getting shocked.....nothing to worry about as long as you aren't poking around under the hood. If you are, you need to turn it off, unplug it, wait several minutes for the power supply caps to discharge, check them with a meter, and ideally have a few resistors with insulated alligator clips laying around to clip across the caps to make darn sure all is safe. Clearly you don't want to trip and fall on it, break the tubes and contact metal parts, while it's running. I wouldn't advise letting the dog/cat piss on it either. Ditto on young children.Some of the chinese tubes can be hard to source. Problem is, getting a accurate schematic so someone can see what needs to be done to convert can be even harder. But the good news is that rectifiers, regulators, and small signal tubes all tend to last a very long time. A preamp that needed re-tubing once a year or two is called a "tube eater". It is not out of line to get ten-twenty or more years. But it is highly dependent on the design, tube quality, and things like power spikes.
So what I am really going to tell you is to NOT roll tubes at first. Instead give the stuff time to break in and for you to become well versed in your equipment's sound. Then and only then should you go ahead and then with only one item at a time. There is no better way to wear out tube sockets and cause aggravation than excessive tube rolling. When the time comes you have two very different ways to go. One, go with a trusted seller who knows your gear and can advise based on your preferences. This will cost the most but has the best chance of success provided you can effectivly communicate your needs. Two, go buy a big mixed lot of tubes off ebay and hope to find a few gems that you really like. Determine make/model and go buy them from a trusted seller.
Rectifier tubes and regulator tubes do indeed make a difference in sound. I can offer no valid reason why this is so but it is.
Current production output/power tubes are pretty good these days so you are in luck there. The rectifiers/regulators are generally okay but not equal in sound to the best NOS. The small signal tubes are where you can waste a lot of money in a hurry so take your time and do your research. In some cases you have a LOT of options. The 12au7 is one of them as there are ...gezz...like 15 different tube numbers you can use. And if the foreplay has enough heater current you can try other tubes like the 6cg7 that I like more and can be had at better prices.
So take your time as there is a lot to learn and a whole lot of people that will take your money. And we haven't even started talking about things like caps and resistors.
I wouldn't let a dog or cat piss on my young children either ;-)
Thanks for the safety advice. It's really nice to know, also, that I don't have to pay up the ass for good power tubes (very interesting about the regulators/rectifiers -- I'll give it a try sometime).On the rolling front, I'm not a total novice to tubes... it's just that I've never handled anything bigger than a 6DJ8, and the tubes have always been inside a chassis so this is the first time I get to watch them glow.
I'm generally skeptical about any outlandish audio claim, so I wasn't sure how tube rolling would make much sense, given that they're all made to the same specifications. As it turns out, they're pretty loose specifications, but I didn't know that at the time. My eyes were really blasted open when I swapped the tubes in my X-CAN V3 headphone amp and those in my X-10D tube buffer, which hadn't be used in a long while (it was the first valve thingy I had, just to see if I'd like it or not). This swap was a pair of JAN Philips 6922 for a pair of Mullard ECC85s. Holy crap, did the Mullards make everything that much better. If the amp was worth the $300 I paid for it with the stock tubes, the Mullards pushed it up to probably twice that. There was more of everything. I experimented with various other types of ECC83/85/88 (in different applications; I know you can't use a 12AX7 in a 6DJ8 socket). BTW, I highly recommmend giving some 6AQ8/ECC85s a go in the X-CAN. I didn't know that the guy who sold me the X-10D had put a different kind of tube in it than what was intended, but in those two components (made for 6DJ8/6922s), the ECC85s encountered no problems whatsoever over the course of about a year. It's a safe and very effective swap. Can't say anything about that substitution in other equipment, though.
So back on track: naturally, I'm interested in rolling a bit, seeing how revelatory it was with the X-CAN head amp. Paradise was just a tube swap away from the pedestrian stock valves. In that spirit, I think I'm going to buck your advice (sorry) and go at it slowly, one component at a time. First priority is the ASL if it still has its stock Chinese tubes, second is the Ming Da. After that, I dunno. Rolling is going to be a complete barrel of monkeys.
About eBay lots: I had never thought of that before and found that there are numerous lots of absurd numbers of used old tubes ( fancy some Telefunken 12AU7s? ). I'd get one of them, but some 95% of them would be totally useless to me because I haven't got any equipment that takes it. I downloaded the TDSL program, by the way... maybe that could shed some light on some of the unknown types in these lots. It's a great resource.
This post is made possible by the generous support of people like you and our sponsors: